Android java.lang.IllegalArgumentException: Servic

问题:

I have a setup that looks something like this:

class MyFragment implements SomeEventListener {

    Application mAppContext;    

    boolean mBound;
    boolean mDidCallUnbind;
    MyIBinder mBinder;
    ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mBound = true;
            mBinder = (MyIBinder) service;
            mBinder.getThings();...
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            mDidCallUnbind = false;
            mBound = false;
            mBinder = null;
        }
    };

    ...

    @Override
    public void onSomeEvent() {
        mAppContext.bindService(...);
    }

    void unbindService() {
        if (mBound && !mDidCallUnbind) {
            mDidCallUnbind = true;
            mAppContext.unbindService(mConnection);
        }
    }

    @Override
    public void onPause() {
        unbindService();
        super.onPause();
    }
}

However, I am still seeing the error in the title from time to time: java.lang.IllegalArgumentException: Service not registered being generated when unbindService() is called. Am I missing something silly, or is there more going on? I should note that there may be more than one of this same fragment in existence.

Edit

Since no one actually seems to be reading the code, let me explain. unbindService() does not call Context.unbindService(ServiceConnection) unless the service is bound (mBound) and it had not previously been called before the onServiceDisconnected(...) callback was hit from a possible previous call to unbindService().

That in mind, are there any cases where Android will unbind your service for you such that the service would become unbound but onServiceDisconnected would not be called thus leaving me in a stale state?

Also, I am using my Application context to do the initial binding. Assume something like:

@Override
public void onCreate() {
    mApplication = getContext().getApplicationContext();
}

回答1:

I realize this question has already been answered. But I think there is reason to go into why people are making this mistake.

The issue is really with the training docs. http://developer.android.com/reference/android/app/Service.html shows a correct implementation while https://developer.android.com/guide/components/bound-services.html in the 'ActivityMessenger' shows a Very INCORRECT implementation.

In the 'ActivityMessenger' example onStop() could potentially be called before the service has actually been bound.

The reason for this confusion is they are using the bound service boolean to mean different things in different examples. (mainly, was bindService() called OR is the Service actually connected)

In the correct examples where unbind() is done based on the value of the bound boolean, the bound boolean indicates that the bindService() was called. Since it's queued up for main thread execution, then unbindService() needs to be called (so queued to be executed), regardless of when (if ever) onServiceConnected() happens.

In other examples, such as the one in http://developer.android.com/reference/android/app/Service.html. The bound indicates that the Services is Actually bound so that you can use it and not get a NullPointerException. Note that in this example, the unbindService() call is still made and the bound boolean doesn't determine whether to unbind or not.

回答2:

Use mIsBound inside doBindService() and doUnbindService() instead of in the ServiceConnection instance.

ServiceConnection mConnection = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        mBinder = (MyIBinder) service;
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        mBinder = null;
    }
}; 

...

public void doBindService() {
    bindService(new Intent(this, MyService.class),
        mConnection, Context.BIND_AUTO_CREATE);
    mIsBound = true;
}

public void doUnbindService() {
    if (mIsBound) {
        unbindService(mConnection);
        mIsBound = false;
    }
}

This is how it's done in http://developer.android.com/reference/android/app/Service.html

回答3:

java.lang.IllegalArgumentException: Service not registered means that you weren't bound to service when unbindService() was called.

So in your case, onSomeEvent() was never called before call to unbindService() in onPause()

回答4:

Another possible reason for this exception might be that unbindService is called by the wrong Context. Because services can be bound not only by Activities, but also by other instances inherited by Context (with the exception of BroadcastReceivers), even by other Services, be sure that unbindService is called by the context that has bound the Service and not by the bound Service itself. This would yield directly the above exception "Service not registered".

回答5:

I have the exact same issue with my application. Every now and then I get IllegalArgumentException. I guess the special case is caused when the service is unbound and the onPause is called before onServiceDisconnected. So I would try Synchronized things to ensure correct execution.